Advocaat has already added Sebastian Coates and Adam Matthews to his defensive options but is insistent any other additions will have to be of requisite class, rather than signed just to make up the numbers.
The experienced Dutch manager oversaw the club’s run to Premier League safety over the last nine games of the 2014-15 season and then performed a U-turn to join on a permanent basis after originally rejecting the chance to take over.
Asked how many more signings he wants, he said: “Three, maybe four.
“It is still very quiet on the transfer market, in England as well. It’s strange. But we still hope that we can get three extra players in the squad. That makes everything a little bit easier.
“What I have said already – and we discussed it with Lee and with the president at the end of last season – we need more competition in the squad.
“We now have two with Coates and Matthews, but hopefully we will still try to get some other ones in as well. We are all working very hard to get the right players in, but that is not so easy.
“Everybody thinks abroad that England is the country of the money, so we have to be very careful with the money, we have to bring the right players in who can compete with the other players.”
Sunderland are understood to be pursuing a series of targets with Zenit St Petersburg defender Nicolas Lombaerts, Dynamo Kiev’s Jeremain Lens and West Ham’s Stewart Downing among them, although Advocaat was giving nothing away.
He said: “I can only tell you things if I know 100 per cent when they are coming, because now I start saying all the good things and maybe tomorrow they say they didn’t do it.
“Let’s wait and see what happens in the next days and weeks.”